AWT-F-93 (Nov-93) Association of Water Tecllnologies Association of Water Technologies, Inc. 5th Annual Convention & Exposition Water Technologies '93, 7 to 10 November 1993 Caesars Palace, Las Vegas, Nevada The Role of Polymers In Water Treatment Applications And Criteria for Comparing Alternatives Robert W. Zuhl, P.E. and Zahid Amjad, Ph.D. Lubrizol Advanced Materials, Inc. (Cleveland, OH) Lubrizol ..,--..Carbosperse K-700 Water Treatment Polymers @2007 The Lubrizol Corporation,all rights reserved. * Formerly BFGoodrich Performance Materials. ** Formerly Good-Rite K-700 Water Treatment Polymers. Table of Contents ABSTRACT~.....................................................................................................................................1 INTRODUCTlON ........................................................................................................................... . AN OVERVIEW OF POL YMERS ............................................................................................... .. SYNTHETIC POL YMERS.............................................................................................................1 PoIymerizationMethods..........................................................................................................1 Polymerization Processes.................................. .......................... ................. ...... ........ .............2 Polymer Characteristics................ ...... ......... ....... ..... ............. .............. ........ ........... ............. .....3 Parameters Typiiying Polymer Properties and Specifications.... ............ ...... ...... ........ ...... ........5 Differatces Between Water Treatment Polymers....................................................................7 1HE ROLE OF POLYMERS IN WATER TREATMENT APPliCATIONS..............................9 Overview ................................................................................................................................9 HistoIy.....................................................................................................................................10 Deposit Contro\ Mecbanisms........................... ...................... ...................... ...... .....................II CRITERIA FOREVALUATING WATER TREATMENT POLYMERS....................................12 EXPERIMENTAL PROCEDURES.................................................................... ............................12 RESULTS AND DISCUSSiON......................................................................................................12 Products Evaluated. ........................... ..................................................... ............................ .....13 Calcium Carlxmate Inhibition.................. ....... ............. .............. ......... ......... ............................13 Calcium Ion Tolerance............................................................................................................13 Calcium Phosphate InIubition..................................................................................................14 Calcium Phosphonate InIubition................... ........................................................ ...................14 Iron Stabilization................................................................................................. ....................14 Iron Oxide Dispersion........ .................... .................................................................................14 SilIlJlated Boi1er Water Treatment Conditions....................... ................................................14 CONCLUSiONS.............................................................................................................................15 ACKNOWLEDGMENTS...............................................................................................................16 REFERENCES................................................................................................................................16 TABLES AND FIGURES TableI:Polymer Molecular Weight Measurement Methods..... ......... .................................19 Table 2:Parameters Typifying Water Treatment Polymer Properties and Specifications.....20 Table 3:Appearance of Competitive Water Treatment Polymers Supplied as Uquids.........20 Table 4:Comparison ofTwo 5,000 Mo1ecu1ar Weight Polyacrylates................................21 Table of Contents (continued) Table 5:Comparison of Two 2,000 Molecular Weight Polyacty\ates....................................21 Table 6:Types ofWater Treatment Polymers........................................................................22 Table 7:Role of Polymers as Deposit Control Agents in Cooling and Boi1er Water Treatment App1ications.............................................................................................22 Table 8:BFG's Criteria for Evaluating Water Treatment Polymers........................................23 Table 9Testing Procedures for Evaluating Water Treatment Polymers................................24 Table 10:Commercia1Iy Available Products Tested.................................................................28 Figure 1:Typica1 MoIecu1ar Weight Determinations for GOOD-RITE K-752 and K-732 PoIyacryIates..................................................................................................30 Figure 2:Quantity of Caustic Soda Needed to Neutralize GOOD-RlTE K-7028 and K-7058 PoIyaayIates to a Desired pH......................................................................30 Figure 3:Chemical Structure for Three Homopolymers..........................................................31 Figure 4:Chemical Structure for Four Acrylate Copolymers..................................................31 Figure 5:Cooling Water Treatment Prognuns.........................................................................32 Figure 6:Calcium Carbonate Scale Inhibition for Competitive Polyacrylates (Under Stressed Test Conditions).............................................................................33 Figure 7:Calcium Carbonate Scale InIubition for Competitive PolyaayIates (Under Moderate Test Conditions)...........................................................................34 Figure 8Calcium Carlxmate InIubition for Products (Under Moderate Test Conditions)......34 Figure 9:Calcium Ion Tolerance ofGOOD-RlTE K-752 and K-732 as a Function ofTemperature........................................................................ .................................35 Figure 10:Calcium Ion Tolerance ofGOOD-RlTE K-700 Polyacrylates and Competitive Deposit Control Agents................................ ........................................36 Figure 11:Calcium Ion Tolerance for Various Copolymers......................................................36 Figure 12:Calcium Phosphate InIubition...................................................................................37 Figure 13:Calcium HEDP InIubition..........................................................................................37 Figure14:Iron Stabi1ization.......................................................................................................38 Figure 15:Iron Oxide Dispersion for Competitive CWT Polymers....................... .....................38 Figure16:Iron Oxide Dispersion for Competitive BWT Polymers Before and After Thermal Treatment ................................................................. ,. ........... ..... .... .... ........39 Figure17:Hydroxyapatite Dispersion for Competitive BWT Polymers Before and After Thermal Treatment............. .......... ............... ................... ..........................39 ABSTRACT Watertreatmenttechnologyhasmadesignificantadvancessincetheintroductionof syntheticwater treatmentpolymers in the1950s.A widerangeof homopolymers,copolymers,andterpolymersare availableforusebywatertreatmentformulators.Thispaperprovidesaguidelineforevaluating alternative polymers. INTRODUCTION Thispaperreviewssyntheticpolymersandspecificallythoseusedfordepositcontrolinthewater treatment industry.The parameters by which polymers may be characterized arediscussed.The role of polymersandcriteria forcharacterizingtheirpropertiesarepresented.Thecriteriaforevaluating water treatment polymers were used to compare several commercially availablepolymers.The results indicatethatBFGoodrich'sGOOD-RITEK-700polymersprovideexcellentperformancewhich meets or exceeds that of competitive products. AN OVERVIEW OF POLYMERS The word "polymer" has Greek origin from the words "poly" (many) and "mer" (part). A polymerisasubstancemadeof giantmoleculesformedbytheunionof manysmallmolecules (monomers) into long chains.Generally,organic polymers have carbon backbones such that the links between the monomer consist of carbon-carbon bonds. Polymersmaybeeithernaturalsuchastanninsandlignosulfonatesorsyntheticsuchaspolyacrylic acids and acrylate copolymers. SYNTHETIC POLYMERS Polymerization Methods Polymerization refers to the bonding of two or more monomers to produce a polymer.Polymerization isalsoanychemicalreactionthatproducessuchabonding.Polymerizationmethodsforsynthetic polymersincludeprecipitation,solution,suspension,emulsion,andbulkasdiscussedbelow.Allof thesepolymerizationmethodshavetheadvantageofheatandviscositycontrolduringthe polymerization.The desired product properties dictate the choice of the polymerization process. Precipitation Polymerization Inprecipitationpolymerization,allreactantsareinitiallysolubleinthepolymerizationsolvent. Polymerizationproceedsinsolutionuntilthepolymerreachesacriticalmolecularweightwhen precipitationof thepolymeroccursduetopolymerinsolubilityinthesolvent.Polymerizationthen proceedsintheheterogeneousmediumbyabsorptionof monomerandinitiatorintothepolymer particles. Solution Polymerization Insolutionpolymerization,allreagentsincludingthepolymericproductremainsolubleinthe polymerization solvent throughout the reaction. Suspension Polymerization In suspension polymerization, droplets (50 to 500 mm) of a water insoluble monomer are suspended in water by means of a suspending agent (usually less than 0.1weight % of the aqueous phase).Both the suspending agent andagitation are necessary in order to keep the monomer droplets fromcoalescing. Byreusinglargeamountsof dispersingagent(> 1 weight%),verysmallmonomerdropletscanbe producedwhichgivepolymerparticlesizerangingform0.5to10 mm.Theprocessisthencalled dispersion polymerization. Emulsion Polymerization In emulsion or latex polymerization the polymerization of monomer only occurs with monomer thatis contained within the micelles (colloidal dispersion) that are formedin water by means of a surfactant. These colloidal dispersions are generally stable, and, once formed,do not need agitation to maintain the colloidalstate.A hydrophilicmonomerisemulsifiedinwaterandpolymerizationisinitiatedwitha water soluble initiator. Inversion Emulsion Polymerization In inverse emulsion, a hydrophilic monomer is emulsified in a non polar organic solvent. Bulk Polymerization Bulk polymerization is the polymerization of the neat monomer(s). Polymerization Processes Reportedly, there are over 50 polyacrylate manufacturers in the UnitedStates.Many of these products areusedinternallyinapplicationsthatdonotdemandtheconsistenthighqualityandperformance requirements of the water treatment industry.Less than a dozen manufacturers are activelysupplying thewatertreatmentindustry.Notsurprisingly,therearewidevariationsinthemanufacturing processes as wellas the product appearance,consistency,andphysicalproperties of thepolyacrylates offered. Manufacturersof water treatmentpolymerssuppliedto water treatmentformulatorsusea varietyof manufacturing techniques.For example, BFGoodrich uses differentsolution polymerization processes fortheGOOD-RITEK-700polymers.Thechoiceof apolymerizationprocessdependsupon 2 severalconsiderationsincludingtechnologyalternatives,productperfonnanceandapplication requirements, and economics. Solutionpolymerizationistheprimarymethodformanufacturingwater treatmentpolymersusedas scaleanddepositcontrolagents.Solutionpolymerizationprocessvariablesincludepolymerization medium(water,solvent),initiator/catalyst,chaintransferagent,monomer(s),temperature,timeof reaction,and agitation.For brevity we will not discuss these variables here.However,it is important to note that polymer manufacturingcomplexity increasesproportional to thenumber of monomersin part because of the different properties and reaction rates of individual monomers. Polymer Characteristics Polymers may be characterized by several parameters including molecular weight, tacticity, end groups, branching, residual monomers, and homogeneity or heterogeneity as discussed below. Molecular Weight A polymersampleconsistsof varying("short"and"long")chainlengthsasopposedtoamonomer sample where allmoleculeshave exactly thesame length.Hence,a polymer sampledoesnothavea uniquemolecularweight,unlikeamonomerwhichhasapreciselydefinedmolecularweight.A polymer sample is characterized by anaverage molecular weightand a molecular weight distribution. The actualnumber depends upon the measurementmethodandthere may beconsiderableassociated bias. Table1 providesalistingof molecularweightmeasurementmethodsamongwhichgelpermeation chromatography(GPC)andviscosityarethetwomostfrequentlyusedbywater treatmentpolymer manufacturers.The major measurements used tocharacterize the molecular weightof a polymer are summarized below: - Mw = -Mn= = -M. = - Mw'Mn = weight average: number average: emphasizes the central portion of the molecular weight distribution emphasizes the low molecular weight fraction highmolecularweightfraction;thelargerthisiscomparedtoMw,themore high molecular weight fraction is present viscosity average: polydispersity: usedtocomparedatafromgelpermeation chromatography(Ope)molecularweight measurements;closetotheweight-averagemolecular weight measuresthebreadthofthemolecularweight distribution;thesmaller thisnumber,thenarrower the distribution 3 Figure 1 illustrates typical molecular weight determinations for two commercial polyacrylates. Tacticity Monomersmaycontainatomicgroupsthatarenotinvolvedin the polymerization reactionthatform the polymer backbone.These groups become pendant to the main chain.The pendant groups may be arranged in a regular manner about the polymer backbone.This gives rise to polymer tacticity. Whenallthependantgroupsareononesideof theplanarzigzagpolymerchain,thepolymeris isotectic.Whenthependantgroupsarelocatedalternatelyonoppositesidesof theplaneof the polymer chain,the polymer issyndiotactic.If thedistribution of thependant groups are random,the polymer is atectic. End Groups Initiator moleculesareusedto commence thepolymerizationprocess.A fragmentfromtheinitiator will bond with the monomer to start a chain.The initiator fragmentis then attached to one end of the polymer chain,thus becoming an"end group" when the polymer chain stops growing due to chemical reactions that prevent monomer addition to the chain end, another "end group" is formed. Branching During the polymerization process, chemical reactions take place on the backboneof a polymer chain causing the formation of a new polymer chain attached to the original one.This phenomenon is known as branching. Residual Monomers Polymerizationreactionsorthelinkingof monomerstoformlargechainsaresubjecttochain termination reactions.Thus,at the end of a polymerization reaction,unreacted monomers or residual monomers will be left admixed with the polymeric product. Homogeneity and Heterogeneity When only one monomer is involved in the polymerization process, the product is homogeneous.For example, if two monomers A and B arecopolymerized,andboth A and B are equally reactive in the polymerizationreactions,thenmonomerA andBwillberandomlydistributedinallof thepolymer chains, and the product is homogeneous.However,a heterogeneous polymer is made,if monomer B islessreactivethenmonomerA.In thiscase,theinitiallyformedpolymerchainscontainlarger amounts of monomer A vs.monomer B.As the concentration of monomer A decreases, the polymer chains formed later in the reaction will contain more ofthe copolymerized monomer B.Further, within each chain, the distribution of monomers A and B would not be random. 4 Parameten Typifying Polymer Properties and Specifications Mostof thewater treatmentpolymerssuppliedtofonnulatorsaresuppliedasliquidsolutions.The polymers may be characterized by a variety of parameters as shown in Table 2 and discussed below: Water treatment polymers are typically water solutions.However, powdered sodium salts are supplied and used for special applications. Appearance Water treatmentpolymerappearanceisanaestheticsratherthanaperformanceissue.Thegoalof manufacturers and fonnulators should be a consistent product ...batch to batch, lot to lot, and shipment after shipment.The polymer manufacturer should have procedure in place to ensure that the product meets a visual appearance specification and is free from any contamination. Theappearanceof onepolymercomparedtoanothermaydiffergreatly.Examplesof theproduct literature descriptions for the"Appearance"of severalcompetitive water treatmentpolymerssupplied as liquids are shown in Table 3. Total Solids Totalsolids isa measurementof the nonwater componentofa polymer.Thehigher the totalsolids the greater the specific gravity and viscosity of a product.The total solids for a particular polymer are normally limited by product stability during storage conditions and/or handling considerations. Totalsolidsmeasurementsareusedto verifythattheproperlevelof ingredientshavebeenusedto manufacturethepolymer.Apolymermanufacturer'sproductapprovalshouldbebasedona specification thatstatesanacceptable totalsolids rangewhichistypically themidpointplusor minus one (1) percent (%). Polymer manufacturersusea varietyof testmethodsfordeterminingproduct totalsolids.Ideally,a totalsolidstestprocedureshouldbebasedonremovingthevolatileor liquidcomponentfromthe productwithoutburningor degradingthesyntheticorpolymericcomponent.Sincethelate1970s, BFGoodrich has been using a highly reproducible microwave drying that provides a rapidmethodfor total solids and volatiles determinations.} Active Solids The active solids of a polymer is the difference between the total solids and counter ions added by post polymerizationneutralizationtypicallywithsodiumhydroxide.Postpolymerizationneutralizationis frequentlynotthe only source of sodium ions ina polymer.Thus,activesolidscan not be measured directly.Therefore, active solids values are normally reported as a typical value (calculated) rather than a measurement. 5 It is important to remember that only the synthetic polymeric component of a product notthe counter ionsfromneutralizationprovidesvalueaddedperformance.Unfortunately,mostpolymer manufacturers do not report active solids. Molecular Weight Aconsistentmolecularweightiscriticaltoapolymer'sperformance.Unfortunately,thetest proceduresformolecularweightdeterminationsareveryexpensiveandtimeconsumingandare therefore not well suited for use as quality control tests.Molecular weight test methods are likely to be run by the analyticaldepartmentof polymer manufacturer's R&D organization but are not typicalfor manufacturingoperations.Polymermanufacturerstypicallydefineaproductbytotalsolidsand viscosityspecificationswhicharecloselyrelatedto apolymersmolecular weight.It isalsopossible although very time consuming to develop correlations of total solids and viscosity to molecular weight. BFGoodrich usesGPCmolecular weightmeasurements2 aswellasviscositymethodsformolecular weight determinations. Measurements of pH are used to verifY thata product has been produced to establishedspecifications and is direct indication of the extent to which a polymer is neutralized. Viscosity Apolymer'sviscosityasdiscussedpreviouslyisdirectlyrelatedtomolecularweight.Therefore, viscosity measurements are a means to verifY that a product is within established specification. BFGoodrich uses Brookfield Viscosity measurements as a method to verifY that each polymer is within established molecular weight tolerances.Product approval is based on an established specifications and a specific test procedure (i.e., 25C, RVF # spindle, and rpm) for each product. Acid Number Acid number measurements are a means to verifY that a copolymer is within established compositional tolerances. Specific Gravity Specific gravity provides a measurement of a product's density.Although specific gravity is a relatively easytesttorun,theinformationitprovidespertainingtoaproduct'scompositionvs.wateris redundant to total solids measurements. Color measurements such as Gardner (yellow), Lovibond yellow,and Lovibond red may be used as an indicator of a product's appearance. 6 Other Parameters Thearea varietyof other parameterssuchasturbidity,haze,iron,andresidualmonomer levelsthat maybeof interestforspecificwatertreatmentpolymersand/orforparticularapplications.A brief discussion of each of these parameters follows. Turbidity and haze measurements are not typical quality control parameters.However, turbidity and/or hazemeasurementsmayprovideameanstoverifYthatapolymermeetsanestablishedcriteriafor appearance. Water treatmentpolymerstypicallycontainlowlevelsof ironasabyproductof themanufacturing processor which werepresentintherawmaterials.However,ironmeasurementsarenota typical quality control test.Only in rare cases will polymer iron levels be a concern.A polymer maycontain excessive iron levels if it turns black when fully neutralized with caustic soda. Unreactedorresidualmonomer(s)maybeahealth/safetyworkexposure,productionprocess efficiency,or regulatoryissue.Residualmonomersarenota typicalqualitycontroltest.However, periodic testing of a residual monomer levels may be used by a polymer manufacturer to ensure that the production process is operating properly or to meet a regulatory agency requirement for new chemical substances. BFGoodrich makes certain that all the OOOD-RITE K-700 polymers conform to established criteria by rigorously controlling manufacturing production process parameters.BFGoodrich applies statistical processcontroltomanufacturingprocesscontrolparametersastheprincipalmeansforensuring quality constituent product quality.In addition, a variety of quality control tests to measure parameter such as those discussed above are used as a means for confirming that each product meets established requirements. Differences Between Water Treatment Polymers The followingdiscussion wasoriginallydeveloped by BFGoodrichduringmid1992andprovided to RCavano of ScrantonAssociates,Inc.forusein the AWT's"Raw MaterialSpecification Manual.,,3 Althoughmuchof thediscussionbelowappearsintheAWTmanualtherehavebeenseveral modifications and additions. Acrylate based water treatment polymers are normally polymerized asacids but notallpolymerization processes are the same.Polymers are typically neutralized with sodium hydroxide after polymerization to various degrees in order to: Provide pH values above the lower DOT limit for corrosive materials, and/or Ensure product stability in the drum, and/or Meet specific customer requirements. 7 However, polymer neutralization adds inactive solids and thus higher pH values Imply greater gaps between total and active solids and Necessitate lower total solid levels in order to supply products with manageable viscosities Accordingly, in addition to molecular weight properties, it is important to examine the pH, total solids, andactivesolidsof competitivepolymersinorder toensure"anapplesto applescomparison."The examplesshowninTables4and5providecomparisonsof two~ 5 , O O Oandtwo~ 2 , O O Omolecular weightpolyacrylatesandpresentaguidelineforhowwatertreatmentformulatorscancompare "functionallyequivalent"polymers.ItisobviousfromtheanalysisshowninTables4and5 thata water treatment formulator is obtaining a higher value in terms of active polymer content with Products B and D vs. Products A and C, respectively. Another way to understand the differences between water treatment polymers supplied at different pH valuesistoobtainor developneutralizationCUIVesforwatertreatmentpolymerssuchasshownin Figure 2 for GOOD-RITE K-7028and K-7058polyacrylates ( ~ 2 , O O Oand~ 5 , O O Omolecular weight respectively).BFGoodrich providesneutralization curves forGOOD-RITE K-700polymers supplied as liquids. Extending the discussion above, it is logical and in practice has been foundthat concentrated polymers (thosesuppliedathighertotalsolidsandlowerpHvalues)morereadilyfacilitatethepreparationof more concentrated water treatmentformulations.In addition,polymerssupplied athigher totalsolids andlowerpHvaluesmeanslesspackagingmaterialsandfreightcostsperactivepoundof polymer supplied to water treatment formulators. Most polymer manufacturers use aqueous polymerization processes.However,solvent polymerization processes that result in the manufacturer of products andpolyacrylates in particular withperformance characteristics that are superior to aqueous polymers. 4,5 One such polymerization process is used by BFGoodrich for manufacturing GOOD-RITE K-732 and K-752polyacrylates.Thedistinguishingpropertiesof GOOD-RITEK-732andK-752polyacrylates vs.other polyacrylates of the same molecular such as those made by aqueous polymerization processes (e.g., GOOD-RITE K-7058 and K-7028 polyacrylates) respectively include: Exceptional calcium ion tolerance (facilitating the operation of cooling systems at higher cycles of concentration),6 Greater thermal stability (comparable to polymaleates and polymethacrylates), 7 and Better silt dispersion. 8 8 Elaboratingonthesecondpointabove,Masler7 concludedthefollowingbasedonhistestingof polymers under simulated boiler water treatment conditions (PH 10.5, 250C,18 hr): Polyacrylates (manufactured by BFGoodrich's solvent polymerization process),polymethacrylates, and polymaleates all undergo some thennal degradation. Polyacrylates displayed about the same resistance to thennal degradation as do polymethacrylates. Polyacrylates are more thermally stable than polymaleates. DubinandFulks4 concludedthat"polymerstructure,molecularweightandeventhemethodof manufactureandchoiceof solventwillstronglyinfluencetheactivityof apolymer.Thepractical significanceof thisisthatgrossdescriptionsof polymerssuchaspolyacrylateor copolymersdonot accuratelydescribeapolymeraccuratelyordefineitsperformance,especiallyunderdifferentwater conditions. " BFGoodrich believes that"it is often desirable to use a polymer product in which the molecules are as similaraspossible,,6ortohaveapolymerwithanarrowmolecularweightdistribution.However, others9 havefoundthatpolyacrylateswithbroadmolecularweightrangesaregenerallymorecost effectivethanpolyacrylateswithnarrowmolecularweightranges.Regardlessof whetherbroador narrow molecular weight distributions are optimal, there is a consensus that molecular weight isa key factor in determining the optimal polymer(s) for a particular application.4,9,lO,1l IRE ROLE OF POLYMERS IN WATER TREATMENT APPUCAnONS Oveniew Deposit control methods for water treatment applications include: Maintaining water chemistry below saturation levels by controlling the: Cycles of concentration: pH Temperature Pretreatment of feed waters Threshold treatments by controlling blowdown by sulfuric acid addition by controlling flow rates, heat loads, etc. viamechanical(e.g.,reverseosmosis)orchemical(e.g., clarification) means using chemicals at sub stoichiometric dosages 9 History Table6providesasummaryof thevarious typesof polymersusedasdepositcontrolagentsbythe water treatment industry.Figures 3 and 4 show the structures forseveral homopolymers andacrylate copolymers,respectively.AdditionalinformationisprovidedbyWilkesl2 inhisrecentNACE CORROSION/93paperentitled"AHistoricalPerspectiveof theScaleandDepositControl-(1943-1993)." Theuseofsyntheticwatertreatmentpolymers(polyacrylates,polymethacrylates,hydrolyzed polyacrylamide,acrylicacid/acrylamidecopolymer,andstyrenemaleicanhydridecopolymers)dates back to the1950s.12 The earlysyntheticpolymers used werehighmolecular weight(100,000+Mw) homopolymers of acrylic acid.With the passage of time,lower molecular weight polyacrylates as well aspolymethacrylatesandpolymaleicacidswerefoundtobemoreefficacious.Researchershave shown thatpolyacrylatemolecular weightisanimportantconsiderationrelativetoperformance.IO,ll Eventually,copolymersof acrylicacid,methacrylicacid,andmaleicacidwerefoundtoprovide improved performance characteristics for specific applications. In the late1970s, Betz LaboratoriesintroducedtheDianodicIIstabilizedphosphatecoolingwater treatment program which incorporated the use of an acrylicacid I hydroxypropylacrylate(AA/HP A) copolymer.Reportedly,theAA/HP A copolymertechnologywhichBetzpatentedandusedforthis application wasnotoriginallyintendedforuseincoolingwater treatmentbutinthepulpandpaper industry.TheDianodicIIprogramdominatedtheheavyindustrialcoolingwater treatmentmarket placeforanumberof yearsasitprovidedanenvironmentallyacceptablealternativetochromate programs. Inthemid1980s,CalgonCorporationintroduceditspHreeGUARDcoolingwatertreatment programbasedonanacrylicacidIsulfonicacid(AAlSA)copolymercalledTRC-233.This copolymertechnologywastoutedashavingand"improvedoperatingconditionsbyeliminatingor minimizingacidfeed,removedthepotentialfordepositformation,andincreasedcyclesof concentration."l3 Subsequently,a barrageof technicalpaperstoutedsuccessfulapplicationsof nonchromatecooling watertreatmentprogramsorpolymersforuseintheseprogramsincludingalkalineall-organic, 14, 15 phosphate-based, 15, 16,17molybdate-based,18 and alkaline-zincI9.These papers and several others20,2l,22,23 pointoutthatthesecrettothesuccessfulapplicationof nonchromatecoolingwatertreatment programswastheevolutionof copolymertechnologythatiscapableof supportingthealternative corrosion inhibitor programs. The success of the Betz Dianodic II program is largely responsible for triggering efforts by other water servicecompaniesandmerchantmarketpolymermanufacturerstodevelopalternativepolymer technology.Therapidresearchanddevelopmentperiodoccurredduringthe1980sandledtothe introductionof a varietyof new merchantmarketpolymers.Thesenewcopolymersasa classhave beentargetedtoprovidespecificperformanceproperties.However,theseproductshavebeen progressively more expensive and several are very special niche products. 10 The role of water treatmentpolymersasdepositcontrolagents incoolingandboiler water treatment programs issummarizedinTable 7.Wilkes12 providesa reviewof the functionsandmechanismsof polymers as deposit control agents.Other paperslS,16,20,21,24outline the generic components used in non chromate cooling water treatment programs and how these programs should be selected and applied. 16 Deposit Control Mechanisms Themajornonchromatecoolingwatertreatmentprogramsinusetodayandtherolesof synthetic polymers are summarized below: CWTProgram All-organic Stabilized phosphate Molybdate-based Alkaline zinc Polymer Functions Ca-phosphonate inhibitor, dispersant Ca-phosphate inhibitor, dispersant Ca-phosphonateinhibitor,Ca-phosphateinhibitor,zincstabilizer, dispersant Ca-phosphonate inhibitor, zinc stabilizer, dispersant Macdonald16 preparedanexcellentguidelinearticleentitled"ChoosingtheCorrectCooling-Water Program"whichprovidesaframeworkforidentifYingthebestprogramforaparticularsite.This article includes a diagram reproduced in Figure 5 which presents the most appropriate pH range for the cooling water treatment programs noted above. Boilerwatertreatmentprogramsinusetodaymaybecategorizedandtheirtreatmentobjective described as outlined below: "Precipitation" "Carbonatecycle"programsdependuponthedispersionof calciumcarbonateasboiler sludges.Normally,naturalorganicpolymerssuch asstarch andligninderivativesare usedin carbonate cycle programs. "Phosphatecycle"programsrelyupontheprecipitationanddispersionof calciumphosphate sludge(ideally calciumhydroxyapatite)to minimizeaccumulationson heattransfersurfuces. Syntheticpolymersareusedtoensurethatthesludgeremainsfluiduntilremovalvia blowdown. "Coordinatedphosphate"programsaretypicallyusedinboilersoperatingat800psigand above.Alkaline and acid phosphates (e.g., mono-,di-,and trisodium) are used to control free causticthataccumulatesinrestrictedflowareas.Neutralizingamineandoxygenscavengers are used (usually fedseparately) as appropriate.Synthetic polymers are used to disperse iron-containing suspended solids and stray calcium compounds. 11 "Chelant"programstypicallyusechelatingagentsuchasEDT A or NT A tocomplexfeedwater calcium or magnesium so itcan not formboiler scale.Synthetic polymers are required to disperse suspendedironcompoundsandanysaltsthatprecipitateasa resultof fluctuationsinfeedwater hardness and/or treatment program upsets. "All Polymer"programs rely on the stabilizing properties of polymers asalternatives to EDT A and NT Ainchelantprograms.Polymersalsodisperseironandothersuspendedsolidsinthese programs. Accordinglytheroleof polymersinboilerwatertreatmentprogramsisasludgeconditioners, dispersants, and hardness stabilizers. In summary, the mechanisms for deposit control usingpolymers incoolingand boiler water treatment applications include Sequestration and Solubilization: Threshold Inhibition: Crystal Modification: Dispersion: EXPERIMENTAL PROCEDURES bymaintainingand/orextendingthesolubilityof sparingly soluble materials by preventing the precipitation of scale forming salts by distorting the formationof scalantcrystalssuch that the will not adhere to equipmentsurfaces andare more readily dispersed bypreventingdepositionofsuspendedmatterand preventing flocculation The water treatmentindustry does nothave any wellrecognizedstandard test methods forevaluating polymers forcoolingandboiler water treatmentapplications.TheeffortsofNACE's T-3A-8fWork Group todevelopa screening test forevaluatingcalciumcarbonate inhibitors typifiesthedifficultyin achievinga consensusforaspecifictestmethod.25However,thereareseveralparametersthatare routinelyusedtoevaluateperformance.TheseparametersarereflectedinBFGoodrich'scriteriafor evaluating water treatment polymers shown in Table8.The experimental laboratory procedures used to evaluate the performance of various deposit control agents are described in Table 9. RESULTS AND DISCUSSION ThetestproceduresandcriterianotedinTable9forscaleinhibition,ironstabilization,ironoxide dispersion,simulated boiler water treatmentconditions,andproduct use considerationswere usedto evaluate the efficacy of the commercially available deposit control agents noted in Table10. 12 BFGoodrichproductswhichwereevaluatedincludedGOOD-RITEK-752,K-732,K-7028,and K-7058 K-775acrylateand K-781, K-797,and K-798acrylate terpolymers. GOOD-RITEK-775acrylatecopolymerisa newproduct.Thus,manyof BFGoodrichstandard screening test data are not yet available and therefore do not appear in this paper for this product. Calcium Carbonate Inhibition Figure 6 presents the calcium carbonate inhibition under high hardness and alkalinity conditions (BFG's stirredthresholdinhibitiontest)forcompetitivepolyacrylates.Theresultsindicatethatmolecularweightpolyacrylatesoutperform molecularweightpolyacrylates.Inaddition, BFGoodrich'sGOOD-RITEK-700polyacrylatesoutperformcompetitiveproductsof thesame molecular weight.For both molecular weight groups, BFGoodrich's solvent polymerized polyacrylates (K-752andK-732)providedsuperiorperformance.TheperformanceofBFGoodrich'swater polymerizedpolyacrylates(K-7028andK-7058)wassecondintheirrespectivemolecularweight group to GOOD-RITE K-752 and K-732 polyacrylates, respectively.Under the stressed conditions of this test,theexceptionalcalcium ion toleranceof GOOD-RITEK-752andK-732polyacrylatesmay explain the performance observed. Figure 7 present the calcium carbonate inhibition forseveralscale controlagentsunder moderate test conditions.TheresultsparallelthosefromtheSTITconditions.However,therelativedifference between products is not as great. Theperformanceof severalproductstoutedfortheircalciumcarbonateinhibitionpropertiesare compared against competitive copolymers in Figure 8.The results generally indicate that commercially available copolymers and terpolymers do not perform as well as HEDP and homopolymers.It appears thatpolymercarboxylcontentiscriticaltocalciumcarbonateinhibitionandthelowerthepolymer carboxyl content, the poorer the performance. Calcium Ion Tolerance BFGoodrich uses two test procedures for evaluating the calcium ion tolerance of polymers as noted in Table8 anddescribedinTable9.Thelong-termmethod6 istimeandlaborintensivebutprovides graphic results.The short-term method26 provides a quick and reliable comparative tool. The long-term calcium ion tolerance of GOOD-RITE and K-732polyacrylates asa function of temperatureisshowninFigure9.6 AlthoughnotshowninFigure9,theperformanceof other polyacrylatesinthe2,000to5,000molecular weightrangeissignificantlylower thanGOOD-RITE K-752polyacrylateandtypicallytoleftandbelowthelinedescribingthecalciumiontoleranceof GOOD-RITE K-732 polyacrylate. Figure10presentstheresultsof BFGoodrich's testingof calciumiontoleranceusingtheshort-term methodforcompetitivepolyacrylatesanddepositcontrolagents.Aswiththecalciumcarbonate inhibitiontesting,GOOD-RITEK-700polyacrylatesoutperformcompetitiveproductsof similar molecular weights. 13 The calcium ion tolerance of competitive copolymers isshown in Figure11.The data indicate that the SS/MA copolymer, the AA/SA copolymers,and the acrylate terpolymers exhibitsuperior calcium ion tolerance in comparison to the polyacrylates shown in Figure 10. Calcium Phosphate Inhibition Theresultsof BFGoodrich'stestingof competitivepolymersforcalciumphosphateinhibitioninthe presence and absence of soluble iron are shown in Figure12.The data indicate that the performance of all polymers is adversely impacted by the presence of iron.The greater the levelof iron, the lower the performance.In general, copolymers containing two (2) different monomers donot provide the same levelof highperformanceasdoterpolymerscontainingthreemonomericgroups.Amongthe copolymers,GOOD-RITE K-775providesthebestperformance.Similarlywiththeterpolymers, GOOD-RITE K-798 followedclosely by GOOD-RITE K-781is best.Under test conditions up to andincluding1ppmiron,GOOD-RITEK-797iscomparabletotheotherterpolymersandis superior to all other products tested. Calcium Phosphonate Inhibition Figure13presentstheresultsforcalciumphosphonate(HEDP)inhibitiontestingof competitive products.The conclusions drawn from the data in Figure 13are similar to those for calcium phosphate inhibition testing inFigure12.Specifically,terpolymersoutperform copolymersandGOOD-RITE K-798 provides the best performance. Iron Stabilization Theresultsof BFGoodrich'stestingof theironstabilizationpropertiesof competitivepolymersare shown in Figure14.Thedata onceagainindicate thatterpolymersoutperform copolymersandthat GOOD-RlTE K-781is the best product followed by GOOD-RITE K-798. Iron Oxide Dispersion Figure 16 shows the results ofBFGoodrich's iron oxide dispersion testing of competitive cooling water treatmentpolymers.TheresultsshowthatthewellknownSS/MAcopolymerprovidesexcellent performancecomparabletoGOOD-RITEK-798acrylateterpolymer.However,GOOD-RITE K-781acrylate terpolymer andAA/SAINIprovide better performance than either SS/MA or K-798. Further, the three AA/SA copolymers do not perform as well as the other products tested. Simulated Boiler Water Treatment Conditions BFGoodrich's efforts to evaluate the performance of several commercial polymers promoted for use in boilerwatertreatmentapplicationswasfirstreportedin1982?Asimilartestmethodology incorporating anautoclave (see ThermalStability inTable9)wasusedtoevaluate competitive boiler water polymers.Preliminary results were reported at the1990 AWTSpring Conference in Las Vegas, NY.The results of this woJi?1 which is still in progress, are shown in Figures16 and17 for iron oxide and hydroxyapatite dispersion, respectively.The data indicate excellent thermal stability for the sodium 14 polymethacrylateandthetwopolyacrylatesevaluatedatboth150and250C.Thebaseline performance forthe twoacrylate terpolymers is better than forthehomopolymerstested.However, the thermal stability of the acrylate terpolymers is not as good even though the absolute performance at 150 and 250C is better than for the homopolymers. A comparison ofthe two acrylate terpolymers which have the same baseline performance indicates that thermalstabilityasdeterminedbyretentionof performancefollowingthermaltreatmentisbetter for GOOD-RITE K-781acrylate terpolymer thanthecompetitiveAAlSNNS terpolymer.Twoof the threemonomersusedtomanufacturetheseacrylateterpolymersarethesame.Accordingly,we speculatethatthethirdmonomerisakeyfactorinexplainingthebetterperformancefor GOOD-RITE K-781acrylate terpolymer. CONCLUSIONS The information presented herein leads to the following conclusions: Synthetic polymers playa significant role in CWT and BWT programs Not all polymers are created equal Compare polymer peIformance and properties including pH, total solids, and active solids Solventpolymerizedpolyacrylatesprovidesuperiorperformanceforhighhardnessand/or alkalinity conditions - Copolymer composition and structure significantly impact perrormance in the presence of iron Polymer selection should be based on several criteria Copolymershavespecificnicheswherephosphates,phosphonates,molybdates,and/orzincare water treatment program components - BWT polymer selection should be basedon performance criteria reflectinguse conditions and regulatory considerations CWTpolymerselectionshouldbebasedonperformancecriteriarelevanttothespecific program 15 ACKNOWLEDGMENTS The authors express their thanks to The BFGoodrich Company,Specialty Chemicals for permitting us to prepare and present this paper. References l.TheBFGoodrichCompany,"TotalSolidsViaMicrowave,"TechnicalBulletinGR-MWTS Test Procedure, Cleveland, OR, 1986. 2.TheBFGoodrichCompany,"MolecularWeightbyGelPermeationChromatography," Technical Bulletin GR-MWGPC, Cleveland, OR, 1986. 3.Association of Water Technologies,"Raw Materials Specifications Manual,"AWT,Arlington, VA,1993. 4.L.DubinandK.E.Fulks,"TheRoleof WaterChemistryonIronDispersantPerformance," CORROSION/84, Paper No.118, NACE, Houston, TX,1984. 5.A Yeoman and P.Sullivan,"Polymer I HEDP Blends for Calcium Carbonate Deposit Control," Cooling Tower Institute,1989 Annual Meeting, Paper No. TP 87-06, Houston, Tx, 1989. 6.The BFGoodrich Company, "GOOD-RITE K-700 Polyacrylates for Use in Water Treatment Applications," Technical Bulletin GC-77, Cleveland, OR, September 1983. 7.W.F.Masler, "Characterization and Thermal Stability of Polymers for Boiler Water Treatment," International Water Conference, Paper No. IWC-82-37, Pittsburgh, P A,1982. 8.The BFGoodrich Company, Confidential Customer Files. 9.B.L.Libutti,IG.Knudsen,andR W.Mueller,"TheEffectsof Antisca1antsonFoulingby Cooling Water," CORROSION/84, Paper No.119, NACE, Houston, TX,1984. 10.P.A.Thomas and M.A.Mullins,"A Current Review of Polymeric Structures and Their Practical SignificanceinCoolingWaterTreatment,"CORROSION/85,PaperNo.130,NACE, Houston, Tx, 1985. 11.Z.AmjadandW.F.Masler,"TheInhibitionof CalciumSulfateDihydrateCrystalGrowthby PolyacrylatesandtheInfluenceof MolecularWeight,"CORROSION/85,PaperNo.357, NACE, Houston, Tx, 1985. 16 12.IF.Wilkes,"A Historical Perspective of Scale and Deposit Control,"CORROSION/93, Paper No. 458, NACE, Houston, TX, 1993. 13.B.C.BoffardiandG.W.Schweitzer,"AdvancesintheChemistryof AlkalineCoolingWater Treatment," CORROSION/85, PaperNo.132, NACE, Houston, TX,1985. 14.D.A.Little,IE.Waller,andC.Soule',"AlkalineAll-OrganicCoolingWaterTreatment," Cooling Tower Institute,1987 Annual Meeting, Paper No. TP 87-5, Houston, TX 1987. 15.W.F.MaslerandZ.Amjad,"AdvancesintheControlof CalciumPhosphonatewithaNovel Polymeric Inhibitor,"CORROSION/88, Paper No.11, NACE, Houston, TX, 1988. 16.RW.Zuhl,Z.Amjad,andW.F.Masler,"ANovelPolymericMaterialforUseinMinimizing CalciumPhosphateFoulinginIndustrialCoolingWaterSystems,"CoolingTowerInstitute, 1987 Annual Meeting, PaperNo. TP 87-7, Houston, TX,1987. 17.G.A.Crucil,IRMacdonald,andE.B.Smyk,"RoleofPolymersintheMechanismsand Performanceof Phosphate-BasedCooling WaterTreatmentPrograms,"InternationalWater Conference, Paper No. IWC-87 -40, Pittsburgh, P A,1987. 18.KF.Soeder andIS.Roti,"Molybdate-BasedCooling Water Treatment:New Developments whichExpandTheirApplicationAreas,"InternationalWaterConference,Paper No.IWC-87-12, Pittsburgh, PA,1987. 19.G.A.CrucilandRH.Schild,"AnAlternativeCoolingWaterTreatmentProgramforthe Replacement ofChromates,"Cooling Tower Institute,1988Annual Meeting,Paper No.TP 87-11, Houston, TX,1988. 20.E.B.Smyk,IE.Hoots,KE.Fulks,andKP.Fivazzani,"TheDesignandApplicationof Polymers inCooling Water Treatment Programs,"CORROSION/88,Paper No.14,NACE, Houston, TX,1988. 21.IP.TenyandCrystalW.Yates,"CurrentCoolingWaterCorrosionControlTechnology," International Water Conference, Paper No.IWC-90-13, Pittsburgh, PA, 1987. 22.T.IYoung,"The Proper Use of Modern Polymer Technology inCooling Water Programs," AWT, Third Annual Convention, Lake Buena Vista, FL,1990. 23.TJ.Young, "The Use of Zinc for Corrosion Control in Open Cooling Systems,"AWT,Spring Conference, San Antonio, TX,1991. 24.IRMacdonald,"ChoosingtheCorrectCoolingWaterTreatmentProgram,"Chemical Engineering, New York, NY, January 19,1987. 17 25.R.W.Zuhl,"NACE T-3A-8fWork Group's Efforts to Develop a Calcium Carbonate Threshold InhibitionScreeningTestforCoolingWaterTreatmentApplications,"CORROSION/88, PaperNo. 431, NACE, Houston, TX, 1988. 26.TheBFGoodrichCompany,GOOD-RITEK-XP82andK-XP83PolyacrylateScaleI Deposit Control Agent,"Technical Bulletin GC-XPIWP, Cleveland, OR, August1987. 27.Z.Amjad,"ThermalStabilityofPolymersforBoilerWaterTreatmentApplications," BFGoodrich Internal Technical Report, Avon Lake, OR, August 1990. 18 Table1 Polymer MolecularWeightMeasurementMethods Freeze Point Depression Boiling Point Elevation Osmotic Pressure Vapor Pressure Lowering Viscosity Light Scattering Ultra centrifugation I-' I.D Sedimentation GelPermeation Chromatography Table 2 Parameters TypifyingPolymerPropertiesand Specifications Form Appearance Total Solids(%) Active Solids(%) Molecular Weight (M,.) pH Viscosity(cpat 25C) Acid Number (mgKOH/g drypolymer) Specific Gravity Color Recommended specification parameter forhomopolymers Recommended specification parameter forcopolymers Table3 Appearanceof CompetitiveWaterTreatmentPolymers SuppliedasLiquids ProductType SolventpolymerizedPAAs waterpolymerizedPAAs Appearance Cleartohazy,colorlesstoambercolored Lightamberwithaslighthaze Lightstraw Waterwhitetoamber,slightlyhazy Lighttoambercolored Cleartoslightlyhazy Clearstrawcolored PAAwithphosphinategroupsCleartoslightyturbidyellow SodiumpolymethacrylateClearamber Clearpaleyellow PolymaleicacidAmber AA/AcrylamidecopolymerStrawcolored MA/EA/VoActerpolymerCleartoslightlyturbidamber MaleicanhydridecopolymerAmberwithaslighthaze SS/MAcopolymer AA/MAcopolymer Acrylateestercopolymer Sulfonatecopolymer AA/SAcopolymers AA/ SAterpolymers PAA MA EA SS =Polyacrylicacid =Maleicacidormaleic =Ethylacrylate =Sulfonatedstyrene Clearamber Paleyellowandclear Cleartocloudy,ambertoslightlypink Clear,darkbrown Clearyellow Clear Cleartoslightlyhazy Waterwhitetoamber,cleartoslightly hazy Clearyellow Waterwhitetoamber,cleartoslightly hazy AA= anhydride voAc= SA= Acrylicacid Vinylacetate Sulfonicacid 20 tv I-' Table 4 Comparison of Two::=5,000 Molecular Weight Polyacrylates Two...5,000 molecular weight PAAs have the following typical properties: Product AProduct B Total solids(TS)48%50% Active solids(AS)43.5%.49.2% pH3.62.5 EstimatedReported How much of Product B plus NaOH and water isrequired tobe equivalent to100pounds of Product A? Equivalent active solids: Product B(0.492)=100lb(product A)x (0.435) =88.4Ib 50%NaOH required toraisepH of Product B to pH 3.6: lbNaOH=88.4 lb Product B x (12IbNaOH I100 lb Product B) =10.6 pounds Water required todilute Product Band NaOH mixture: Water=(100- 88.4 - 10.6)Ib 1.0lb ....100 lbProduct A...88.4lbProduct B + 10.6lbNaOH +1.0 lbwater 100lb Table 5 Comparisonof Two::=2,000Molecular WeightPolyacrylates Two...2,000 molecular PAAshave the followingtypicalproperties: ParameterProduct C Total solids(TS)48%55% Active solids(AS)45.1%.51.7 % pH3.63.7 EstimatedReported How much of Product D plus NaOH and water isrequired to be equivalent to 100pounds of Product C? Equivalent active solids: Product D(0.517)=100lb(product C)x (0.451) =87.21b NopH adjustment aspH Product C...pH Product D: Water required todilute Product D: Water=(100- 87.2)lb =12.81b ....100IbProduct C...87.2lbProduct D ...U..8lbwater 100lb Table 6 Typesof Water Treatment Polymers Homopolymers Polyacrylic Acid(PAA) Polymethacrylic Acid(PMAA) Polymaleic Acid(PMA) Copolymersof AcrylicAcidand/or MethacrylicAcidand Acrylamides Acrylate esters Maleic acid or maleic anhydride tv tv Sulfonic acidmonomers Copolymersof MaleicAcidor MaleicAnhydrideand Acrylic or methacrylic acid Sulfonic acidmonomers A1kenes Acrylate and alkenylesters Table 7 Role of Polymers asDepositControl Agents in Cooling and Boiler Water Treatment emmIT Scale inhibitors for - Carbonate andsulfate scalesXX - CalciumphosphateXX -Calcium phosphonateX General purpose dispersants of particulates -Silt,mud,etc.X - Iron oxideXX Sludge conditionersX Metal ion(iron, zinc,etc.) stabilizersX Copolymers are required Table 8 BFG's Criteria forEvaluatingWater TreatmentPolymers Laboratory Screening Tests Scale inhibition - Calcium carbonate (static and stirred) Calcium sulCate Barium sulCate Calcium oxalate Calcium phosphate(ortho,poly) Calcium phosphonate(HEDP,AMP) - Silica Isilicate Calcium fluoride Particulate dispersion - Kaolin clay - Calcium carbonate - Iron oxide - Hydroxyapatite Metal ion stabilization and sequestration - Iron - Zinc - Manganese - Calcium - Magnesium - Calcium Imagnesium Product UseConsiderations Corrosivity NaOH neutralization (quantityrequired vs.pH) Hydrolytic stability(pH< 2 and pH> 12) Thermal stability - Simulated storage conditions - Simulated boiler water conditions Tendency to cause foaming Calcium iontolerance (long-term and short-term) Chlorine compatibility - Polymer stability in thepresence of polymer - Chlorine stability inthepresence of polymer Aquatic toxicity(rainbow trout,daphnia,algae) 23 Table 9 TestingProceduresforEvaluatingWaterTreatmentPolymers Testing Procedures Threshold Inhibition Testing Methods Static CaC03 Test 1.Preparesupersaturated solutionsof CaC03(Ca +2= 560 ppm as CaC03, (HC03)-1=630 ppm as CaC03, and (C03) -2= 30 ppm as CaC03) at a pH of 8.3 con-taining 0 to 5.0 ppm scale inhibitor. 2.Store in capped 500-ml Erlenmeyer flasks and place in a 66C oven for 24 hours without agitation. 3.Filterthrougha0.22-l'mMilliporefilterpaper,and analyze for Ca +2concentration using standard EDTA titration. Static CaS04 Test 1.Prepare supersaturated solutions of 6,220 ppm CaS04 at a pH of 7.0 containing 0 to 2.0 ppm scale inhibitor. 2.Store incapped four-ounce jars and place ina 66C oven for 24 hours without agitation. 3.Filterthrougha0.22-l'mMilliporefilterpaper,and analyze for Ca +2concentration using standard EDTA titration. Static BaS04 Test 1.Prepare supersaturated solutions of 118 ppm BaS04 at a pH of 7.5 containing 0 to 3.5 ppm scale inhibitor. 2.Store in capped four-ounce jars and place in 25C water bath for 24 hours. 3.Filter through a O.22-l'm Millipore filter paper, and deter-mine concentrationof Ba +2usingatomic absorption spectroscopy. STIT for CaC03 1.Prepare supersaturated solutions of CaC03 (Ca +2= 1,000 ppm as CaC03 and (HC03)-1= 1,200 ppm as CaC03) at a pH of 7.5 to 8.0 containing 0,7.5,15 and 25 ppm scale inhibitor. 2.Stircontinuouslyforonehourwhilemaintaining temperature at 80C using animmersionheater and maintainingconstantwatervolumebycontinuously adding distilled water dropwise. 3.After one hour,discontinue heating and stirring,then allow the sample to cool. When the sample is cool, filter through0.22-l'mMillipore filter paper and determine concentration of Ca+2 using standard EDTA titration. Calculation %Inhibition=[Is- [ IbX 100 [ Ie- [ Ib Where: ]s=Ca +2or Ba +2concentration(ppm)inthe sample containing scale inhibitor after testing. ]b=Ca +2orBa +2concentration(ppm)intheblank sample after testing. ]e=Ca+2 or Ba+2 concentration (ppm) initially. Deposit Control Testing Methods CaC03 Test 1.Prepare CaC03 solutions (Ca +2=560 ppm as CaC03 and(HC03) -1=630ppmasCaC03)atapHof 8.0 24 containing 0 to 2.0 ppm deposit control agent in double-walled glass reaction vessels. 2.CaC03 depositionis initiated by immersing a heated metal surface in the solution vessel. A temperature dif-ferential is provided by circulating hot water maintained at 681C through the tube and by circulating cold water maintained at 8C through the outside jacket of the reaction vessel. 3.Take samples at various times, filter through O.22-l'm Millipore filter paper, and analyze for Ca +2 concentra-tion using standard EDTA titration. 4.At the conclusion of the test, determine the amount of CaC03 deposited on the tube (heat exchanger surface). CaS04 Test 1.Prepare supersaturated solution of 5,560 ppm CaS04 containing0to2.0ppmdepositcontrolagentina double-walled glass reaction vessel. 2.Continue as in steps 2, 3 and 4 of the CaC03 test. Dlspersancy Testing Methods 1.Prepare a 100 ml slurry containing 5 g clay or 5 g CaC03 and0to20ppmdispersantina100mlgraduated cylinder. 2.Mix samples thoroughly for 30 to 60 seconds. 3.Let samples stand and visually observe the rate of set-tling by noting the interface between the clear and tur-bid regions in the cylinder. Calcium Ion Tolerance Test Method 1.Prepare Ca +2 solutions (Ca +2=625 ppm as CaC03)at a pH of 9.0 with various dosages (0 to 70 ppm) of scale inhibitor. 2.Store in capped 250-ml Erlenmeyer flasks and place in a constant temperature (30 to 75C) water bath for 24 hours. 3.Stir continuously and measure percent transmittance of sample using a fiber optic turbidity probe interfaced with a colorimeter. 4.Plot percent transmittance against scale inhibitor con-centration to determine the onset of turbidity. Total Solids Test Method The BFGoodrich Chemical Group developed an automatic computerized microwave oven procedure for determining percent total solids. They found this test procedure increases both the accuracy and the speed at which results can be ob-tained.(A copy of the total solids test method is available upon request.) Percent totalsolids may also be measured ina vacuum oven. This procedure involves drying a sample for one hour at 100C followed by two hours at 100C under a vacuum of 25 mm of mercury or less. A second alternative is to dry the sample to constant weight under a heat lamp. While the vacuum oven and heat lamp methods of measur-ing total solids give reasonably accurate and reproducible total solids results,the values obtained by these methods may not exactly match those obtained by the more accurate microwave oven technique. Table9(continued) TestingProceduresforEvaluatingWaterTreatmentPolymers CalciumPhosphateInhibition 1.Preparesupersaturatedsolutionofcalciumphosphate[140ppmCa+2, 9.0ppm(P04) -3)]containing0to10ppmofscaleinhibitorin reactioncellsmaintainedat50C. 2.stir continuouslyandmaintainpH8.5bytheautomaticadditionof 0.1MNaOH. 3.After22hours,filter solution through0.22micronfilter paperand analyze filtrate spectrophotometrically for phosphate concentration. 4.Calculateinhibitionusingthefollowingformula: % Inhibition=[(P04lsample- (P04lcontrol]x100 (P04)initial- (P04)control CalciumPhosphonateInhibition 1.Preparecalciumphosphonatesupersaturatedsolution[150ppmCa+2, 15ppmphosphonate(HEDPorAMP),266ppmCl-1,60ppm(HC03)-1,22ppm Na+1)]atpH8.5containing0to10ppmofscaleinhibitor. 2.storeincappedflasksandplacein50Cwaterbathfor20hours withoutagitation. 3.Filtersolutionthrough0.22micron filtratespectrophotometricallyfor phosphonatetophosphate. filterpaperandanalyze phosphateafteroxidizing 4.Calculateinhibitionusingthefollowingformula: % Inhibition=[(phosphonatelsample- (phosphonatelcontrol]x100 (phosphonate)initial- (phosphonate)control IronOxideDispersion 1.Prepare600mLofsyntheticwater[100ppmCa+2,30ppmMg+2,314ppm Na+1,570ppm(S04)-2,60ppm(HC03)-I,264ppmCI-1)]ina800mLbeaker containing1ppmofdispersant. 2.Add0.12gofironoxideandcontinuouslystirslurriesatroom temperatureusingasixpaddlestirrerfor3hours. 3.Measurepercenttransmittanceusingacolorimeter. 4.Calculatepercentdispersionusingthefollowingformula: % Dispersancy=[100- (1.11x% transmittance)] 25 Table 9(continued) TestingProceduresforEvaluatingWaterTreatmentPolymers IronStabilization 1.Preparesyntheticwatersolutions[100ppmCa+2,100ppmMg+2,1,120 ppmNa+1,2,170ppmCl-1,700ppm(S04)-2,153ppm(HC03)-1)]containing 3ppmFe(III)andadd4ppmactivepolymer. 2.AdjustpHofsolutionto7.0andstoreincapped4ozjarsatroom temperaturefor2hours. 3.Filtersolutionthrough0.22micronfilterpaperandanalyze filtrateforironbyatomicabsorptionspectroscopy. 4.Calculatepercentironstabilizationusingthefollowingformula: % IronStabilization=[(iron)sample- (iron)control]x100 (iron)initial- (iron)control ZincStabilization 1.Preparesyntheticwater[60ppmCa+2,20ppmMg+2,202ppmNa+1,36 ppm(HC03)-1,172ppmCl-1,200ppm(S04) -2)]containing6ppmzincand 4.5ppmscaleinhibitor. 2.AdjustpHto8.5andstoreincapped4ozjarsat30Cfor20hours. 3.Filtersolutionthrough0.22micronfilterpaperandanalyze filtrateforzincbyatomicabsorptionspectroscopy. 4.Calculatepercentzincstabilizationusingthefollowingformula: %ZincStabilization=[(Zn)sample- (Zn)control]x100 (Zn)initial- (Zn)control CalciumIonTolerance(Short-TermMethod) 1.PrepareCa+2 solution(10,000ppmca+2)and100mLofpolymer solution(0.1gactivepolymer)atpH8.0. 2.Titratepolymersolutionwithcalciumsolutionat72F(22C)to determinetheonsetofturbidityusingacolorimeter. 3.CalculatecalciumiontoleranceasmgCa+2 per100mgpolymer. 26 Table9(continued) TestingProceduresforEvaluatingWaterTreatmentPolymers Chlorinecompatibility 1.Preparepolymersolution(100ppmasactive)containing240ppmof sodiumhypochloriteatpH9.0. 2.storepolymersolutionsincappedjarsat22Cfor6days. 3.Testpolymerperformanceforcalciumphosphateorcalcium phosphonateinhibition. Hydrolyticstability(pH12) 1.Preparepolymersolutions(10%asactive)atpH1.0(withHCI)orpH 12.5(withNaOH). 2.storeincappedjarsat80Cfor6days.CheckpHdailyandadjust ifnecessary. 3.Testpolymerperformanceforcalciumphosphateorcalcium phosphonateinhibition. Thermalstability 1.Prepareapolymersolution(1%asactive)atpH10.5containing0.3 gramsofsodiumsulfiteasanoxygenscavenger. 2.Heatthepolymersolutioninastainlesssteelreactormaintainedat constanttemperature(150Cor250C)for20hours. 3.Testpolymerperformanceforironoxideandhydroxyapatite dispersion. HydroxyapatiteDispersion 1.Transfer100mlofsyntheticwater[100ppm,Ca+2,30ppmMg+2,314 ppmNa+,571ppmCI-1,200ppm(804)-2,60ppm(HC03)-1]containing0to 2.5ppmpolymersolution(withandw/othermaltreatment)toa100 mlgraduatedcylinder. 2.Add2.5gramsofhydroxyapatiteandmixgentlyfor5minutes. 3.Letslurriesstandfor3hoursandmeasuretransmittance. 4.Calculatepercentdispersionusingthefollowingformula: % Dispersancy=[100- (1.11x% transmittance)] 27 Table10 CommerciallyAvailableProductsEvaluated Acronym HEOP PAA-2M K-7028 PAA-5M AC1000 AC1100 AR-257 AR-900 BS161 NaPMAA PMA MCP SS/MA AA/SA-A AA/SA-B K-775 AA/SA/NI AA/C-l AA/C-7 AA/C-8 NOTES: Product DQ2010 K-752 K-7028 K-732 AC1000 AC1100 AR-257 AR-900 BS161 T960 Be200 BC283 V-TL4 AC2000 BC400 K-775 AC3100 K-781 K-797 K-798 Description l-Hydroxyethylene-l,l-diphosphonicacid ..,2,000M"polyacrylate(PAA) ..,2,000MwPAA ..,5,000M"PAA It!2,000MwPAA It!5,000M"PAA It!2,000MwPAA It!5,000M"PAA Polyacrylicacidcontainingphosphinategroups Sodiumpolymethacrylate Polymaleicacid Maleicacid(MA)/ethylacrylate(EA)/vinyl acetateterpolymer Sulfonatestyrene/maleicanhydridecopolymer AA/sulfonicacid(SA)copolymer AA/SAcopolymer AA/SAcopolymer AA/SA/substitutedacrylamideterpolymer AA/SA/sodiumstyrenesulfonate(SSS)terpolymer AA/SA/SSSterpolymer AA/SA/SSSterpolymer "DO"isanabbreviationforMonsantoCompany's"Dequest- Phosphonates" "K-700"isanabbreviationforTheBFGoodrichCompany'sGOOD-RITE- K-700 polymers "AC"and"T"areabbreviationsforRohmandHaasCompany's"Acumer-"and "Tamol-"polymers "AR"isusedhereasanabbreviationforAlcoChemicalCorporation's "AQUATREATDI AR"series "BC"and"BS"areabbreviationsforFMCCorporation's"Belclene-"and "Belsperse-"products ''V-TL''isusedhereasanabbreviationforNationalStarch's''VERSA-TL-'' polymers 28 I\.) I.D Figure 1 Typical Molecular Weight DeterminationsforTwoPolyacrylates Gelpermeationchromatoaraphymolecularweight determination for Good-rltel K-752 polyacrylate. Q) (I) c:: 8. ~ ... o II CD c 1 Molecular Weight Mn=970 Mw=2,030 Mz=3,690 Mw/Mn=2.1 0'........ 110102 103 104 105 Molecular weight Gelpermeationchromatographymolecularweight determination for Good-riteK-732 polyacrylate. Q) (I) c:: o c.. (I) ~ ... o U Q) CD c 1 Molecular Weight Mn=2,200 Mw=5,070 Mz=9,970 MwlMn=2.31 0', ~~ 110102 103 104 Molecular weight 105 LVo Figure 2 Quantityof50%CausticSodaNeeded toNeutralizeGOOD-RITEK-7028andK-7058 PolyacrylatestoaDesiredpH 14~ I- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ 12 10 I8 0.. 6 4 K-7028 K-7058 & 2 1 ~ - - - - ~ - - - - - - ~ - - - - - - ~ - - - - ~ - - - - - - ~ ~ o1020304050 Poundsof50%CausticSodaper100Pounds ofGOOD-RITEK-700Polyacrylate W I-' Figure3 ChemicalStructures forThree Homopolymers PolyacrylicAcid(P AA) -tCH2CH-rn I C02H PolymethacrylicAcid(PMAA) CH3 I -tCH2CTn I C02H PolymaleicAcid(PMA) -tCHCH-ro II C02HC02H Figure 4 ChemicalStructures for Four Acrylate Copolymers Acrylicacid/R copolymer(AAlR) [-tCH,CH)A( CH,CH+'- INII CO,HR Acrylicacid/Hydroxypropylacrylate copolymer(AA/HPA) [-tCH,